Tooth-crown fastening



UNITED stares PATENT oFFicE.

HANS EMIL SCHMIDT, OF BAD OLDESLOE, GERMANY.

` Toorn-CROWN rAs'rEivING.

Specification of Letters Patent. f

Patented Oct. 5, 1920.

Application filed May 14, 1919:: vSerial No. 297,152.

T 0 alito/0m t may concern:

Be it known that l, lrlANs EMIL SCHMIDT, citizen of Prussia, residing at Bad Oldesloe, Salinenstrasse 17, Germany, have invented certain new and useful Improvements in TootheCrown F astenings, of which the following is a specication.

tween the crown anchor and the root prong, n

bridge or palate plate. A

The invention consists in providing ra rearwardly sloping top bearing` surface on the crown and anchor for the purpose of forming a space behind the front iacetof the crown between the base of the latter and the bottom or" the root, bridge or palate plate and in providing a casting for insertion into said space for connecting the anchor with the root-prong, bridge or plate to forni a coherent body. i

ln employing this attachment, the sockets in the root and the crown may be very narrow, so that neither one nor the other is weakened by boring. Since this attachment is also intended to be used for hall2 crowns, it can also be used for deeply carious roots. Owing tothe junction, the anchor produced by casting finds, in the recess sharply ofset from the socket towa-r'd the back of the crown, a particularly reliable attachment which can withstand a great pressure exerted from below against the back of the crown. rlhis pressure is taken up by the side wall or the recess situated at a short distance from the back of the crown and running parallel to the socket', so that, owing to this direction of the pressure, that part of the anchor, which projects into the socket is nearly completely relieved and for this reason the artilicial tooth will be extraordinarily durable.

At all events, that is to say at any desired size or shape of the root and any position of the root socket, the same construe tion and size of the crown socket and recess and or the anchor can be used, so that artificial crowns can be held in store together with equally shaped anchors. A broken crown therefore can be easily replaced, as

anew casting can be substituted without removing the prong' from the root, as is necessary in known tastenings.

p ln the accompanying drawing:

l`igure l is a vertical section of an artifcial tooth crown embodying my invention.

Fig. 2 is a similar view ot' the crown anchor.' F ig.-3 is a vertical section of a crown attached to a root,'and Figs. 4 and 5 show Vthe crown attached to a bridge and palate plate respectively.

The crown a having a hollow back suraceis provided roi` attaching it to the root,

bridge or palate plate with a sloping basel surface. The dotted A line shown in Fig. l designates the shape of a tooth crown of known construction. The socket I) extends up to the said sloping surface, but it is not bored, as is done in known crowns,`in the center V'or behind the center of the tooth, but in (front of such center, that is to say nearer to the Vlabial part ofthe crown a and therefore can project deeply into the crown. The socket Z) expands into a sharp offset cavity toward the back of the crown, thus forming a trough shaped recess c extending up to the sloping surface. The back wall d of this recess is at right angles to the base e of the recess and runs parallel to the socket Z).

The anchor shown in Fig. 2 fits the socket Z) and the recess c, exactly and forms a tightly fitting prong f and a lateral shoulder g, illiner the recess. Vhen this anchor j", g is mounted in the crown, its outer surface is flush with the bearing surface of the crown 0;.

As all the crowns carried in stock have the same socket Z) and recess c, they can without being further prepared or operated upon be mounted on roots, bridges and the like or interchanged with already mounted crowns.

Vlien the anchor j, g is attached to a root, bridge or palate plate, there will be a space between the bearing surfaces of the crown and the root, bridge or plate, which space is widened toward the back of the crown.l This space will be filled by a casting produced by the aid of a plaster cast model to connect the anchor with the root pin, bridge or the palate plate to form a coherent body.

In Fig. 8 a crown is shown attached to a root 7a, according to the present invention. From this figure it will be seen that, owing to the sloping bearing surface of the crown a, the space between this surface and the surfaceof the root tol be filled up is widened toward the back in such manner that it is very easy to pour in the metal, which connects the root prong z' with-the anvchoiA f, g. v

From Fig. 4 it will be understood that the same advantages are obtained, when A a bridge 7c is to be provided with an artificial toothy the casting connects the crown anchor Y with the bridge directly. The same is'to be said with regardto the palate plate m shown in Fig. 5.

As the wall Z is parallel to thesocket and is situated at a short distance from the back of the crown, there will be .two' lsupporting surfaces on the anchor f, g,

whichy give the. crownA a vsteady hold,` particularly when the pressureis exerted from below'in an `oblique direction against the back ofthe tooth, asV it will vhappen when the bitingof'the lower teeth is very deep,

upper teeth.

and in the direction shown by the arrow in the drawing against the I claim: 'Y

`l. A tooth crown fastening comprising an anchor' including a pin and shoulder. adaptedcto fill upa pin socket within the Yback side of theY crown and a trough-shaped recess projecting 1n said socket, the rear wall of said recess being parallel to the socket and to said anchor, the outer surface of the anchor be-v ing flush with the base surface of the crown,

a mountingrfor the crown, and a fastening means cast between the said pin and the said mounting, the casting forming a coherent body within said anchor and said mounting.

2. An Yartificial tooth crown including a mounting therefor, an anchor embedded in the crown having a base bearing surface sloping downwardly'toward the baclrof the crown and conforming tothe base surface ofthe latter, thereby'forming av space between the mounting andthe crown Vbehind the front face of the latter,'and a fastening piece cast in said spaceforming a coherent body with said anchor and mounting.

3. The combination ofa crown mounting, a crown, an anchor embedded therein, and a casting interposed between the crown and mounting for Vconnecting the latter to the 

